In recent years, there is a case where, in order to control devices, such as an engine, a turbocharger, and an exhaust gas recirculation (EGR), an engine control system divided into an engine control unit (ECU) configured to control an engine body part and an ECU configured to control the turbocharger, the EGR, or the like is mounted.
Since the ECUs which control the above-described devices constituting the engine need to control the engine body part, the turbocharger, the EGR, and the like in cooperation with one another, the amount of communication between the ECUs increases, and calculation loads of the ECUs tend to increase.
If communication delay occurs in a network of the ECUs, it is supposed that control of the engine becomes unstable. For this reason, a communication network which includes a network relay device or a database distribution node so as to prevent the occurrence of communication delay has been suggested (for example, see PTL 1 and PTL 2).